1. Field of the Invention
The present invention relates to a superconducting circuit provided with a Single Flux Quantum (SFQ) circuit using a high temperature superconductor and an interface circuit for the single flux quantum circuit, and is applicable to fields of communication, computing, and instrumentation such as routers for communication, servers, AD converters, samplers, and so on.
2. Description of the Related Art
Conventionally, high temperature superconductor junctions have been thought to be applicable to the SFQ circuits as they are without being shunted by resistance because their current-voltage characteristics are called an overdamp type, and unlike low temperature movement Nb superconductor junctions, the hysteresis in the current-voltage characteristic is sufficiently small. The latch driver circuits which are important as an interface circuit are thought to be unsuitable for the formation of a high temperature superconductor because pulse logic in the SFQ circuit is converted into level logic so as to be usable with an external semiconductor device or the like, which requires hysteresis in the current-voltage characteristic.
Conventionally, in superconducting circuits in which the SFQ circuits using high temperature superconductors and the interface circuits are installed together, the design has to be made to conform to a slight operational region in which the SFQ circuit and the interface circuit can coexist, such as critical current density.
[Patent Document 1]
Japanese Patent Application Laid-open No. 2000-353831